use zookeeper prometheus metric provider to export zookeeper metrics (a…

…pache#10803)

### Motivation
After upgrade zookeeper version to 3.6.2 in apache#8590 and removed AspectJ based metrics for ZooKeeper in apache#10533, the zookeeper's prometheus metric has lost if we start zookeeper by `bin/puldar-daemon start zookeeper`.

Due to zookeeper 3.6.0+ has add internal prometheus metric provider, so we can turn on by default in pulsar.

### Modification
1. turn on zookeeper prometheus metric provider by default in `conf/zookeeper.conf` and use 8000 as default port sync with old zookeeper metric port
2. add grafana panel for new zookeeper metrics
3. remove old prometheus metric provider in `ZooKeeperStarter` and `ConfigurationStoreStarter`.
4. update reference-metric.md doc

conf/zookeeper.conf

@@ -67,3 +67,10 @@ sslQuorum=false
 # (using the same configuration as the secure client port).
 # Default: false
 portUnification=false
+
+## Metrics Providers
+#
+# https://prometheus.io Metrics Exporter
+metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
+metricsProvider.httpPort=8000
+metricsProvider.exportJvmInfo=true

distribution/server/src/assemble/LICENSE.bin.txt

@@ -512,6 +512,7 @@ The Apache Software License, Version 2.0
   * Apache ZooKeeper
     - org.apache.zookeeper-zookeeper-3.6.2.jar
     - org.apache.zookeeper-zookeeper-jute-3.6.2.jar
+    - org.apache.zookeeper-zookeeper-prometheus-metrics-3.6.2.jar
   * Snappy Java
     - org.xerial.snappy-snappy-java-1.1.7.jar
   * Google HTTP Client